Fluidic-pneumatic devices with forces balancing

ABSTRACT

Force balance comprising a beam placed inside an enclosure separated from the outer medium by means of a non-magnetic sealtight wall in which the means for measuring the position deviation and for transmitting the rebalancing force are made by a fluidic regulating device having a blade provided on one end thereof with a magnetic mass cooperating through the seal-tight wall with another magnetic mass placed on one end of the beam.

1 1 July 18, 1972 United States Patent Larmurier [56] References CitedUNITED STATES PATENTS [54] FLUIDIC-PNEUMATIC DEVICES WITH FORCESBALANCING X 5 oo 7 3 l.

m h c S n e "m 345 556 999 111 II/ 325 948 26 203 378 223 e m w m r 0 mM m m w e m. m m 0 E C d n m m e F m e aw mm CFC m m. e 1 v a m A 1 1 23 7 7 l France [22] Fil d; M 6, 1971 Primary Examiner-Charles A. RuehlAttorney-Pierce, Schefiler & Parker [21] Appl. No.:

[ ABSTRACT Force balance comprising a beam placed inside an enclosureseparated from the outer medium by means of a non-magnetic seal-tightwall in which the means for measuring the position deviation and fortransmitting the rebalancing force are made by a fluidic regulatingdevice having a blade provided on one end thereof with a magnetic masscooperating through the seal-tight wallwith another magnetic mass placedon one end of the beam.

[52] US. Cl. [51] Int. Cl. [58] Field of Search 3 Claim, 1 DrawingFigure FLUIDIC-PNEUMATIC DEVICES WITH FORCES BALANCING The presentinvention relates to improvements to force balances of which both themeasurement of the deviation and the transmission of the rebalancingforces are made through a seal-tight wall.

Fluidic pneumatic regulating devices with force rebalancing are alreadyknown. Such devices are particularly disclosed in the French Pat.application No. 70-07134 filed on Feb. 27, 1970 by Compagnie desCompteurs.

The purpose of the present invention is mainly to realize a forcebalance embodying such a regulating device and making use of theadvantages thereof.

The invention has more precisely for its object the provision of a forcebalance comprising a beam submitted to a force and placed inside anenclosure separated from the outer medium by means of a seal-tight wall,means for measuring the deviation of the beam and for transmitting arebalancing force, said means being made by a fluidic regulating devicecomprising at least a flexible blade, a deviation detector with nozzle,an amplifier controlled by said detector and at least a jet rebalancingmeans controlled by the amplifier and acting on said blade, said bladebeing further provided near one end thereof with a magnetic masscooperating through the seal-tight wall with another magnetic mass, saidanother magnetic mass being fixed on one end of the beam, and saidseal-tight wall being made of a non-magnetic material.

Several other features of the invention will now be revealed whenreading the following description with reference to the accompanyingdrawing which shows illustrative and by nomeans limitative embodiment ofthe present invention and in which:

The only FIGURE shows diagrammatically the balance of the invention.

A blade 1, made of a flexible material, has been shown inserted at oneend thereof in a support 8, while a small plate 4 is fixed near theother end of said blade. A nozzle 5 is fed with a fluid from a sourceSo, via a conduct 6 through a pneumatic resistance 7 made for example bya throttle in conduct 6. The nozzle 5 is placed at a short distance fromthe small plate 4 shorter than one fourth of the diameter of the openingof the nozzle. An important pressure variation is thus obtained of thefluid coming from the nozzle 5 and hitting the small plate 4, for aslight displacement of said small plate 4, whereby enabling to detectthe position duration of the blade 1. The output pressure is measured bya pressure-gauge 8 and then provide an information as to the importanceof the deviation. Said output pressure controls a fluidic amplifier 9 ofa known type and whose output signal feeds a jet-blower 10 via apneumatic resistance 11.

Said pneumatic resistance 11 is eventually adjustable and may be made bya needle-valve (apex-angle from 2 to 4") more or less closing a smallthin tube; it is also possible to only use a throttle on the conduct.

The jet coming from jet-blower l0 exerts onto the blade 1 a feed-backaction which rebalances said blade whenever the latter shows a positiondeviation with respect to the equilibrium balance thereof.

The fluidic component which has just been described is separated fromthe mobile equipment of a balance, and this mobile equipment is enclosedin an enclosure limited by a seal-tight wall 12. Said wall is made of anon-Magnetic material and the mobile equipment is made of a beam 13pivotally mounted on a spindle l4.

A force F to be measured is applied on one end of the beam by anysuitable means, for example said force may be the force exerted by afluid blowed on said end via a jet-blower 10a, by a magnetic field, etc.The other end of the beam 13 is provided with a mass 15 made of amagnetic material. When said mobile equipment is on balance, said mass15 is placed at the level of the free end of the blade located at theother side of wall 12.

Said free end of the blade is moreover provided with another magneticmass 16. if the blade 1 is made of steel or other magnetic material, themagnetic mass 16 may be obtained through influence of mass 15 on thesteel of said blade, of which the free end may be bent over.

Thus, when the force F is applied to the mobile equipment, previously onbalance, said mobile equipment is then unbalanced and the mass 15deviates. The deviation of the mass 15 causes a position deviation ofthe blade 1 through mutual action of the magnetic masses 15 and 16. Thisposition deviation is detected by the fluidic component which tends torebalance the blade 1, and the gauge 8 enables to have an information asto the importance of the force F.

The above described device is equivalent to a force balance withautomatic rebalancing, the fluidic component or fluidic regulatingdevice constituting a kind of rebalancing device enabling to transmitthrough wall 12 the deviation of the beam 13 of the mobile equipment forrebalancing the same.

The above described balance device will correspondingly have variousapplications. As an example, said balance may substitute the forcebalance device of the outflow measuring apparatus with control of thevolume mass as described in the French Pat. Application No. 69 22124filed on Jan. 1, 1969 by Compagnie des Compteurs. Said application isobviously only illustrative and the balance may be used with many probesof physical magnitudes displaying forces having low amplitude.

1 claim:

1. Force balance comprising a beam submitted to a force and placedinside an enclosure separated from the outer medium by means of aseal-tight wall, means for measuring the deviation of the beam and fortransmitting a rebalancing force, said means being made by a fluidicregulating device comprising at least a flexible blade, a deviationdetector with nozzle, an amplifier controlled by said detector and atleast a jet rebalancing means controlled by the amplifier and acting onsaid blade, said blade being further provided near one end thereof witha magnetic mass cooperating through the sealtight wall with anothermagnetic mass, said another magnetic mass being fixed on one end of thebeam, and said seal-tight wall being made of a non-magnetic material.

2. Force balance according to claim 1 wherein said blade is fixed to asupport, at the end thereof which is not provided with a magnetic mass.

3. Force balance according to claim 1 wherein the blade is made of amagnetic material and the end of the blade which is provided with amagnetic mass is bent over, whereby the magnetic material of the bladeconstitutes the magnetic mass.

1. Force balance comprising a beam submitted to a force and placedinside an enclosure separated from the outer medium by means of aseal-tight wall, means for measuring the deviation of the beam and fortransmitting a rebalancing force, said means being made by a fluidicregulating device comprising at least a flexible blade, a deviationdetector with nozzle, an amplifier controlled by said detector and atleast a jet rebalancing means controlled by the amplifier and acting onsaid blade, said blade being further provided near one end thereof witha magnetic mass cooperating through the seal-tight wall with anothermagnetic mass, said another magnetic mass being fixed on one end of thebeam, and said seal-tight wall being made of a non-magnetic material. 2.Force balance according to claim 1 wherein said blade is fixed to asupport, at the end thereof which is not provided with a magnetic mass.3. Force balance according to claim 1 wherein the blade is made of amagnetic material and the end of the blade which is provided with amagnetic mass is bent over, whereby the magnetic material of the bladeconstitutes the magnetic mass.